Vacuum-tube apparatus



E. O. SCRIVEN.

VACUUM TUBE APPARATUSI APPLICATION FILED JUNE 21, IQIB. RENEWEDSEPT. I4,920.

1,375,739 Patented Apr. 26, 1921.

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UNITED STATES PATENT OFFICE.

EDWARD O. SCRIVEN, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

VACUUM-TUIBE APPARATUS.

Application .filed June 27, 1918, Serial No. 242,183.

To (ZZZ whom it 722 any concern Be it known that I, EDWARD ScmvnN, acitizen of the United States, residing at New York, in the county of NewYork, State of New York, have invented certain new and usefulImprovements in Vacuum- Tube Apparatus, of which the following is afull, clear, concise, and exact description.

This invention relates to vacuum tube circuits and has for its object toprovide means whereby the grid potential of a tube is maintained at alltimes at a potential different from that of the filament potential, viz.negative.

In the case where a plurality of tubes are connected to act as amulti-stage amplifier it is desirable, especially in the last few tubesof a series, that the grid potential shall always be negative withrespect to the filament potential. If this were not so, or if thepotential of the grid were not sufficiently negative as above stated,the fluctuations of the larger amounts of energy which occur in thelater tubes would cause the grid potential to become positive, therebynot only impairing the amplification efiiciency of the tubes but alsocausing a current in the grid circuit with a consequent loss of thepower in the tube itself. To accomplish this object the inventionprovides that the grid of a tube in the series shall be connected to thefar side (negative side) of a preceding filament so that there shall besufficient voltage drop to the grid as to cause it to be negative inpotential with respect to the filament.

In the drawings illustrative of the invention, Figure 1 shows threetubes having their grids connected to a common wire leading to the farside of the first filament of the series; Fig. 2 shows a circuit inwhich the grid of each tube is connected to the far side of the filamentof the tube next preceding.

As shown in the drawing, with particular reference to Fig. 1, aplurality of tubes 1,

2 and 3 are shown connected between an incoming line 4 and an outgoingline 5 by suitable transformers 6 and 7.

The grids 8 and 9 of tubes 2 and 3 are connected by. a common wire 10 tothe first tube 1. The requisite negative potential relation for grid 12of tube 1 is provided by Specification of Letters Patent.

Patented Apr. 26, 1921.

Renewed September 14, 1920. Serial No. 410,082.

the drop from battery 20 through resistance 13 to filament 11. Since thefirst tube handles relatively small amounts of power, the potentialdifference between grid 12 and filament 11 need not be very great. Thismay be of the order of .1 volt. In tube 2 the requisite potential forgrid 8 is similarly obtained by the drop from battery 20 throughresistance 13, filament 11 to filament 14. This drop may be of the orderof 10 volts. Likewise in tube 3 the requisite drop for grid 9 isobtained over the following circuit: from battery 20, resistance 13,filaments 11 and 14 to filament 16. This drop may be of the order of 20volts. It will be noted that the drop to grids 8 and 9 is obtained bypassing through all the preceding filaments in each case. Resistances 15and 17 are provided in the circuit of grids 8 and 9, respectively, andare of the order of 100,000 ohms. In accordance with this circuit,therefore, the potential relation between the filaments and grids in thetubes, as above set forth, increases along the series of tubes and thusenables increasingly larger amounts of energy to be handled by the tubeswithout causing appreciable current to flow in the grid circuit andimpair the efiiciency of amplification.

In Fig. 2 is represented a circuit wherein a series of tubesl, 2 and 3may be used as an amplifier of modulated waves. For this purpose it isnot necessary that the potential difference between grid and filament insucceeding tubes be increased by so much as in the former circuit asshown in Fig. 1. Therefore it is only necessary in this case to connectthe grid of tube 3, as shown, to the far side of the preceding filamentin tube 2. In this case the grid of tube 1 is connected as describedwith reference to Fig. 1. In tube 2 the grid 8 is connected throughresistance 15 to wire 18, to the far side of filament 11 of tube 1. Grid9 of tube 3 is'connected through resistance 17 to wire 19 to far side offilament 14 of tube 2. By this arrangement the same principle isemployed but the voltage drops to the grids are not so great as shown inFig. 1, because of the needs of the particular adaptation of the device.The usual A and B batteries are designated as 20 and 21, respectively.

It is evident then that the negative potential desired for a grid isobtained from the drop-in potential across the terminals of thefilaments of the preceding tube or tubes.

What is claimed is:

1. A vacuum tube apparatus comprising a plurality of tubes arranged in aseries and each having a cathode and a grid, and means for applying tothe grid of one of said tubes thg potential across the cathode ofanother tu e.

2. A vacuum tube apparatus comprising a plurality of tubes arranged in aseries and each having a cathode and grid, and means for applying to thegrid of one of said tubes the potential across the cathode of apreceding tube.

3. A vacuum tube apparatus comprising a plurality of tubes arranged in aseries and each having a cathode and grid, and means for applying to thegrid of one of said tubes the potential across the cathode of the tubenext preceding.

4. A vacuum tube apparatus comprising a plurality of tubes arranged in aseries and each having a cathode and a grid, and means for causing thediiference in potential between the grid and cathode in succeeding tubesto increase along the series.

5. A vacuum tube apparatus comprising a plurality of tubes arranged in aseries and each having a cathode and a grid, and means for applying toone grid in the series the potential across the cathode of the firsttube of the series.

6. A vacuum tube apparatus comprising a vacuum tube having a filamentand grid, means for heating the filament, a resistance between thefilament and said means, a second tube having a filament and grid, andconnecting means whereby the potential of the grid in the second tube ismade dependent upon the drop across the preceding filament and saidresistance.

In witness whereof, I hereunto subscribe my name this 24th day of JuneA. D., 1918.

EDWARD O. SGRIVEN.

